The present invention relates to a system for connecting a tube to a flexible hose, the system comprising an endpiece disposed at the end of the hose and having first locking means suitable, when in a coupling situation in which a first of the two parts constituted by the tube and the endpiece is engaged in the second of said two parts, for co-operating with second locking means fitted to the tube, the system further comprising a gasket suitable for sealing the link between the tube and the endpiece in said coupling situation.
For example, if it is the tube which is engaged in the endpiece, then the gasket is disposed inside the endpiece and co-operates with the outside face of the tube.
Systems of that type are known in which the gasket is constituted by an add-on annular element, generally an O-ring made of rubber or the like. The gasket must be prevented from moving axially since it must not move when the tube is engaged in the endpiece. Consequently, it is necessary to provide the inside periphery of the endpiece with a housing suitable for receiving the gasket and for holding it in place, which implies that the inside periphery of the endpiece must be provided with a shape that is relatively complex. In addition, the gasket must be put into place in its housing after the other parts of the system that form the endpiece have been assembled together. Such installation is relatively difficult to perform since it must be done with sufficient precision to be certain that the gasket is properly placed in its housing, and in any event it requires an additional step to be performed after the parts of the endpiece have been assembled together.
The French patent application published under the No. 2 717 883 also discloses a connection system in which the gasket is xe2x80x9cintegratedxe2x80x9d in the parts of the endpiece. Thus, that endpiece has an outside ring with an opening through which plastics material is injected after the various component parts of the endpiece have been assembled together so as to make the gasket by overmolding. Nevertheless, overmolding is a difficult operation which requires appropriate injection equipment. In any event, the step of injecting the gasket constitutes an additional step after the various component parts of the endpiece have been assembled together.
The present invention seeks to remedy those drawbacks.
This object is achieved by the fact that the endpiece has first and second rings disposed one after the other on a first of the inside and outside faces of the hose, a xe2x80x9csealingxe2x80x9d gap being organized between said rings, the second ring being closer to the end of the hose than the first, by the fact that the endpiece further includes a tubular body which is disposed on the second of said inside and outside faces of the hose and which extends at least over the region of said second face corresponding to the zone occupied by the sealing gap on the first face, and by the fact that the gasket is formed by a swelling of the hose which is to be found in the sealing gap.
In a system for which the tube is engaged in the endpiece, the first and second rings constitute inside rings disposed inside the hose, while the tubular body is placed on the outside face of the hose. Under such circumstances, the swelling is formed projecting radially inwards and is suitable for co-operating with the outside face of the tube to perform its gasket function.
By means of these dispositions, the gasket forms an integral portion of the system and is not constituted by an add-on part. Because of the nature of the material constituting the hose, which is generally rubber or a thermoplastic material that will creep, the swelling is sufficiently flexible to provide sealing by co-operating with the outside periphery of the tube.
Advantageously, the ends of the rings situated on either side of the sealing gap have means for avoiding injuring the hose on either side of the swelling.
This precaution makes it possible to avoid the hose being damaged or abnormally degraded in the region of the swelling during the lifetime of the connection system, thereby ensuring that the swelling continues to perform its sealing function normally.
In an advantageous disposition, the system further includes an intermediate ring disposed between the first and second rings, and first and second sealing gaps in which respective first and second swellings of the hose are formed are respectively organized between the first ring and the intermediate ring, and between the intermediate ring and the second ring.
Advantageously, the elements constituted by the second ring and by the tubular body extend beyond the end of the hose and carry the first locking means.
By way of example, these first locking means may comprise a resilient locking member such as an elastically deformable ring located in the extension formed in this way.
The invention also provides a method of manufacturing a system for connecting a tube to a flexible hose, in which an endpiece is placed at one end of the flexible hose and said endpiece is fitted with locking means suitable, in a coupling situation in which a first of the two parts constituted by the tube and the endpiece is engaged in a second of said two parts, for co-operating with second locking means fitted to the tube, in which method a gasket is provided suitable for sealing the link between the tube and the endpiece in said coupling situation.
A first known method of that type for making systems in which the tube is engaged in the endpiece consists in assembling the various component parts of the endpiece at the end of the hose, while taking the precaution to provide a housing in the inside periphery of the endpiece for the purpose of containing the gasket, then in placing said gasket (generally constituted by an O-ring of rubber or the like) inside the housing. The need to shape the housing for the gasket naturally complicates manufacture of the parts of the endpiece, and the step during which the gasket is placed in said endpiece constitutes an additional step.
The invention seeks to remedy those drawbacks.
This object is achieved by the fact that to place the endpiece at the end of the hose, first and second rings are placed on a first of the inside and outside faces of the hose, by the fact that a xe2x80x9csealingxe2x80x9d gap is organized between said rings, by the fact that a tubular body is disposed on the second of the inside and outside faces of the hose with the body being placed in such a manner as to extend at least over the region of said second face which corresponds to the zone occupied by the sealing gap on the first face, and by the fact that the endpiece of the gasket is provided by forming a swelling in the hose which extends in the sealing gap.
In this way, the gasket is made and properly installed during assembly of the rings and the tubular body on the hose. Manufacture is thus simplified since any need to add on a gasket or to manufacture it subsequently is avoided and there is no need to provide a workshop with a location for storing parts such as add-on gaskets or injector apparatus for making the gasket(s).
In an advantageous implementation, in order to form the swelling, those of the elements constituted by the first and second rings and by the tubular body that are located on the outside face of the hose are reduced in diameter. This reduction in diameter is advantageously performed by using a swaging step.
Thus, if the system is of the type in which the tube is engaged in the endpiece, the tubular body is on the outside surface of the hose and the diameter of the tubular body is reduced both for fixing it to the hose and simultaneously for making the swelling which forms the gasket. Swaging constitutes a particularly simple manner of achieving this reduction in diameter. It should be observed that swaging can then be performed by simultaneously holding in place the tubular body and the second ring located towards the end of the hose, and by displacing the swaging tool axially going away from said end. In which case, it can suffice to engage the two rings one after the other inside the hose without taking care to provide a sealing gap between the two rings, and it is the swaging movement which tends to move the second ring away from the first and to enable the sealing gap to be obtained while forming in said gap the swelling which forms the sealing ring.
To make a connection in which it is the endpiece which is engaged inside the tube, the tubular body is placed inside the hose and the two rings are placed on the outside of the hose. The reduction in diameter, e.g. by swaging, is then applied to the two rings which are on the outside of the hose.
To form the swelling, it is also possible to increase the diameter of those elements constituted by the first and second rings and the tubular body which are to be found on the inside face of the hose.
To increase the diameter, an expansion tool is inserted inside the hose so as to co-operate either with the tubular body if it is the tubular body which is placed inside the hose, or else with the first and second rings if it is the rings that are placed inside the hose.
It should be observed that this increase in diameter of the inside elements can be combined with decreasing the diameter of the outside elements as mentioned above or can be performed instead of said decrease.
In an advantageous implementation, an intermediate ring is placed between the first and second rings, first and second sealing gaps are formed respectively between the first ring and the intermediate ring, and between said intermediate ring and the second ring, and first and second swellings are formed in the hose, the swellings extending respectively in the first and second sealing gaps.
In this way, two swellings are made which form two gaskets that are axially spaced apart from each other.
Advantageously, at least one of the elements constituted by the second ring and by the tubular body is allowed to project beyond the end of the hose to form an extension, and the first locking means are placed in said extension.
It should be observed that the invention makes it possible to make the gasket either inside the hose if both rings are disposed inside the hose, or outside the hose if both rings are disposed on the hose.